[PATCH 2/2] fpga: Add support for Xilinx LogiCORE PR Decoupler

This adds support for the Xilinx LogiCORE PR Decoupler
soft-ip that does decoupling of PR regions in the FPGA
fabric during partial reconfiguration.

Signed-off-by: Moritz Fischer <mdf@kernel.org>
Cc: Michal Simek <redacted>
Cc: S?ren Brinkmann <redacted>
Cc: linux-kernel at vger.kernel.org
Cc: devicetree at vger.kernel.org
---
 drivers/fpga/Kconfig               |   9 +++
 drivers/fpga/Makefile              |   1 +
 drivers/fpga/xilinx-pr-decoupler.c | 156 +++++++++++++++++++++++++++++++++++++
 3 files changed, 166 insertions(+)
 create mode 100644 drivers/fpga/xilinx-pr-decoupler.c

diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
index 967cda4..e42c7dc 100644
--- a/drivers/fpga/Kconfig
+++ b/drivers/fpga/Kconfig

@@ -69,6 +69,15 @@ config ALTERA_FREEZE_BRIDGE
          isolate one region of the FPGA from the busses while that
          region is being reprogrammed.

+config XILINX_PR_DECOUPLER
+       tristate "Xilinx LogiCORE PR Decoupler"
+       depends on FPGA_BRIDGE
+       help
+         Say Y to enable drivers for Xilinx LogiCORE PR Decoupler.
+         The PR Decoupler exists in the FPGA fabric to isolate one
+         region of the FPGA from the busses while that region is
+         being reprogrammed during partial reconfig.
+
 endif # FPGA

 endmenu

diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
index cc0d364..3f04bcf 100644
--- a/drivers/fpga/Makefile
+++ b/drivers/fpga/Makefile

@@ -15,6 +15,7 @@ obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA)      += zynq-fpga.o
 obj-$(CONFIG_FPGA_BRIDGE)              += fpga-bridge.o
 obj-$(CONFIG_SOCFPGA_FPGA_BRIDGE)      += altera-hps2fpga.o altera-fpga2sdram.o
 obj-$(CONFIG_ALTERA_FREEZE_BRIDGE)     += altera-freeze-bridge.o
+obj-$(CONFIG_XILINX_PR_DECOUPLER)      += xilinx-pr-decoupler.o

 # High Level Interfaces
 obj-$(CONFIG_FPGA_REGION)              += fpga-region.o

diff --git a/drivers/fpga/xilinx-pr-decoupler.c b/drivers/fpga/xilinx-pr-decoupler.c
new file mode 100644
index 0000000..07afdd6
--- /dev/null
+++ b/drivers/fpga/xilinx-pr-decoupler.c

@@ -0,0 +1,156 @@
+/*
+ * Copyright (c) 2017, National Instruments Corp.
+ *
+ * FPGA Bridge Driver for the Xilinx LogiCORE Partial Reconfiguration
+ * Decoupler IP Core.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/of_device.h>
+#include <linux/module.h>
+#include <linux/fpga/fpga-bridge.h>
+
+#define CTRL_OFFSET 0x00
+#define STATUS_OFFSET 0x00
+
+#define CTRL_CMD_MASK          BIT(0)
+#define CTRL_CMD_DECOUPLE      BIT(0)
+#define CTRL_CMD_COUPLE                ~BIT(0)
+
+#define STATUS_STATE_MASK      BIT(0)
+#define STATUS_STATE_COUPLED   ~BIT(0)
+#define STATUS_STATE_DECOUPLED BIT(0)
+
+struct xlnx_pr_decoupler_data {
+       void __iomem *io_base;
+       struct clk *clk;
+       bool enable;
+};
+
+static inline void xlnx_pr_decoupler_write(struct xlnx_pr_decoupler_data *p,
+                                          u32 offset, u32 val)
+{
+       writel(val, p->io_base + offset);
+}
+
+static inline u32 xlnx_pr_decoupler_read(const struct xlnx_pr_decoupler_data *p,
+                                        u32 offset)
+{
+       return readl(p->io_base + offset);
+}
+
+static int xlnx_pr_decoupler_enable_set(struct fpga_bridge *bridge, bool enable)
+{
+       int err;
+       struct xlnx_pr_decoupler_data *priv = bridge->priv;
+
+       if (priv->enable != enable) {
+               err = clk_enable(priv->clk);
+               if (err)
+                       return err;
+
+               xlnx_pr_decoupler_write(priv, CTRL_OFFSET,
+                                       enable ? CTRL_CMD_COUPLE :
+                                       CTRL_CMD_DECOUPLE);